Damping valve devices for vibration dampers which provide a two-fold adjustment are disclosed, for example, in German published patent applications DE-OS Nos. 21 19 531 and 33 03 293. Especially DE-OS No. 21 19 531 shows two series-connected damping valve systems with a blockable bypass passage which serves to bridge one damping valve system. It is in this case disadvantageous that the one or the other damping valve system cannot be selectively actuated. Accordingly, it is not possible to design the required characteristic curve for each particular use situation.
In these known vibration dampers, the damping characteristic curve is essentially varied ony between a setting for soft damping and a setting for hard damping. In order to optimize the driving behavior of vehicles, an externally influenceable damping force variation for more than two stages is desired. Low damping forces are desired in the case of slow driving, for example, for city trips at speeds up to 50 kph; medium damping forces on country roads at speeds up to 100 kph; and, high damping forces for fast highway trips from 120 kph. A slight, that is very soft, damping is provided for the slow driving range only according to considerations of comfort; however, a vehicle with this setting becomes unsafe and unreliable for fast trips. For such cases, an automatic variation of the damping should be provided which is preferably dependent upon the driving speed.